A Dual-Grid Hybrid RANS/LES Model for Under-Resolved Near-Wall Regions and its Application to Heated and Separating Flows

Nguyen, Philipp; Uribe, Juan; Afgan, Imran; Laurence, Dominique

doi:10.1007/s10494-019-00070-8

Cited by 22 publications

(4 citation statements)

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“…A second-order central differencing scheme was used for flow parameters, whereas the turbulent properties were discretized using the van Leer scheme (Van Leer [ 55 ]). The numerical treatment and discretization techniques utilized in this study have already been extensively benchmarked over a wide range of thermal-hydraulic and renewable energy configurations, see Afgan et al [ 56 ], Filippone and Afgan [ 57 ], Guleren et al [ 58 ], Han et al [ 59 ], Wu et al [ 60 ], Wu et al [ 61 ], Wu et al [ 62 ], Kahil et al [ 63 ], Benhamadouche et al [ 64 ], Nguyen et al [ 65 ], Ejeh et al [ 66 ], Ejeh et al [ 67 ], Revell et al [ 68 ], Ahmed et al [ 69 ], Ahmed et al [ 70 ], McNaughton et al [ 71 ] and Abed et al [ 72 ]. The boundary conditions applied in the current study are summarized below:…”

Section: Numerical Modelingmentioning

confidence: 99%

Thermal-Hydraulic Analysis of Parabolic Trough Collectors Using Straight Conical Strip Inserts with Nanofluids

et al. 2021

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In this study, we numerically investigated the effect of swirl inserts with and without nanofluids over a range of Reynolds numbers for parabolic trough collectors with non-uniform heating. Three approaches were utilized to enhance the thermal-hydraulic performance—the variation of geometrical properties of a single canonical insert to find the optimized shape; the use of nanofluids and analysis of the effect of both the aforementioned approaches; the use of swirl generators and nanofluids together. Results revealed that using the straight conical strips alone enhanced the Nusselt number by 47.13%. However, the use of nanofluids along with the swirl generators increased the Nusselt number by 57.48%. These improvements reduced the thermal losses by 22.3% for swirl generators with nanofluids, as opposed to a reduction of only 15.7% with nanofluids alone. The investigation of different swirl generator designs showed various levels of improvements in terms of the overall thermal efficiency and thermal exergy efficiency. The larger swirl generator (H30mm-θ30°-N4) with 6% SiO2 nanofluids was found to be the optimum configuration, which improved the overall collector efficiency and thermal exergy by 14.62% and 14.47%, respectively.

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Section: Numerical Modelingmentioning

confidence: 99%

Thermal-Hydraulic Analysis of Parabolic Trough Collectors Using Straight Conical Strip Inserts with Nanofluids

et al. 2021

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“…Over the last few decades, several studies investigating different aspects of thermalhydraulics components and various modeling approaches related to nuclear power plants have been conducted [4][5][6][7][8][9][10][11][12][13][14][15][16]. However, the safety of nuclear reactors and various incident plans has not received the required numerical consideration to reduce MCCI and the various factors affecting it [17].…”

Section: Introductionmentioning

confidence: 99%

Thermochemical Modeling of Metal Composition and Its Impact on the Molten Corium–Concrete Interaction: New Insights with Sensitivity Analysis

2022

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The characterization of molten corium–concrete interaction (MCCI) has increasingly become a cause of concern because, in the case of a severe nuclear accident, the core could meltdown and release radiation into the environment. The objective of this study was to determine the thermochemical impact of metal content in the corium and analyze the effect of corium metal content on ablation depth, corium temperature, its viscosity and surface heat flux, and production of hydrogen, carbon monoxide, and carbon dioxide. The governing heat transfer equations were solved while considering the various thermochemical reactions in the existing numerical code in a comprehensive way. The developed MCCI model in CORQUENCH was validated against the data available in the literature. Our findings showed that the composition of corium, especially its metal content, has a noticeable effect on mitigating or aggravating the ablation depth and nuclear reactor integrity. We observed that during molten corium–concrete interaction, zirconium plays a significant role and its presence can increase the ablation depth exponentially from 18.5 to 139 cm in the investigated case study. It was found that the presence of zirconium in the corium instigated various thermochemical reactions continuously, and thus the injected water, instead of quenching the molten corium, enhances the temperature by facilitating exothermic reactions. Additionally, due to the presence of zirconium, the production of hydrogen and carbon monoxide increases by 45 and 52 times, respectively and the generation of carbon dioxide becomes zero because the zirconium reacts with carbon dioxide continuously, converting it to carbon monoxide.

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“…grid convergence index (Roache, 1994; Shukla and Dewan, 2019b; Wu and Piomelli, 2016). Studies have been reported using RANS, hybrid computations and LES on the same grid to present differences in flow features obtained and to provide a reasonable comparison for engineering computations (Kang and Sotiropoulos, 2012; Nguyen et al , 2020).…”

Section: Introductionmentioning

confidence: 99%

Computational analysis of convective heat transfer properties of turbulent slot jet impingement

Shukla

Dewan

2021

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Purpose Convective heat transfer features of a turbulent slot jet impingement are comprehensively studied using two different computational approaches, namely, URANS (unsteady Reynolds-averaged Navier–Stokes equations) and SAS (scale-adaptive simulation). Turbulent slot jet impingement heat transfer is used where a considerable heat transfer enhancement is required, and computationally, it is a quite challenging flow configuration. Design/methodology/approach Customized OpenFOAM 4.1, an open-access computational fluid dynamics (CFD) code, is used for SAS (SST-SAS k-ω) and URANS (standard k-ε and SST k-ω) computations. A low-Re version of the standard k-ε model is used, and other models are formulated for good wall-refined calculations. Three turbulence models are formulated in OpenFOAM 4.1 with second-order accurate discretization schemes. Findings It is observed that the profiles of the streamwise turbulence are under-predicted at all the streamwise locations by SST k-ω and SST SAS k-ω models, but follow similar trends as in the reported results. The standard k-ε model shows improvements in the predictions of the streamwise turbulence and mean streamwise velocity profiles in the zone of outer wall jet. Computed profiles of Nusselt number by SST k-ω and SST-SAS k-ω models are nearly identical and match well with the reported experimental results. However, the standard k-ε model does not provide a reasonable profile or quantification of the local Nusselt number. Originality/value Hybrid turbulence model is suitable for efficient CFD computations for the complex flow problems. This paper deals with a detailed comparison of the SAS model with URANS and LES for the first time in the literature. A thorough assessment of the computations is performed against the results reported using experimental and large eddy simulations techniques followed by a detailed discussion on flow physics. The present results are beneficial for scientists working with hybrid turbulence models and in industries working with high-efficiency cooling/heating system computations.

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A Dual-Grid Hybrid RANS/LES Model for Under-Resolved Near-Wall Regions and its Application to Heated and Separating Flows

Cited by 22 publications

References 44 publications

Thermal-Hydraulic Analysis of Parabolic Trough Collectors Using Straight Conical Strip Inserts with Nanofluids

Thermal-Hydraulic Analysis of Parabolic Trough Collectors Using Straight Conical Strip Inserts with Nanofluids

Thermochemical Modeling of Metal Composition and Its Impact on the Molten Corium–Concrete Interaction: New Insights with Sensitivity Analysis

Computational analysis of convective heat transfer properties of turbulent slot jet impingement

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